Custom return path domain in Email Delivery

Summary:

Can a free tier user request to change custom return path in email delivery?

Content (required):

I read this page for instructions: https://docs.oracle.com/en-us/iaas/Content/Email/Reference/deliverabilitybestpractices.htm

and I'm trying to get support to change my custom return path. But the joke is that on Free Tier, I cannot interact with customer support. Catch 22. What should I do?

Version (include the version you are using, if applicable):

OCID: ocid1.user.oc1..aaaaaaaabkac5wothdyduio36kd5vdd27jmln2ajpqastgkkwj2iq2o2xfta

Code Snippet (add any code snippets that support your topic, if applicable):